In recent years, a flat plate detection technology has made a great progress. The flat plate detection technology may be divided into a direct type and an indirect type, a key component of an indirect flat plate detector is a flat plate detector (FPD) for acquiring an image. For example, FIG. 1 shows a schematic diagram of an X-ray flat plate detector of prior art. As shown in FIG. 1, the X-ray flat plate detector mainly comprises an X-ray conversion layer 11, a light detection device 12 (in general, a PIN type photodiode), and an electronic signal detection device 13 (in general, a thin film transistor). When X-rays are irradiated on the X-ray conversion layer 11, the X-ray conversion layer 11 converts the X-rays into visible light, and then the light detection device 12 converts the visible light into an electronic signal and the electronic signal is stored. Under action of a driving circuit, the thin film transistor is turned on, and the electronic signal converted by the PIN type photodiode 12 is transmitted to a data processing circuit through the thin film transistor, the data processing circuit further performs operations of amplification, analog/digital conversion or the like on the electronic signal to finally obtain an image information.
Generally, the PIN type photodiode 12 and the thin film transistor 13 in the X-ray flat plate detector are arranged in parallel, thus there is a strong interference therebetween, and since the manufacturing process of the X-ray flat plate detector is complex, it is difficult to further improve detection precision of the X-ray flat plate detector. FIG. 2 shows a schematic diagram of an X-ray flat plate detector disclosed in a U.S. patent application with a publication number of US 20120038013 A1, the X-ray flat plate detector is an X-ray flat plate detector in a vertical layout. As shown in FIG. 2, the X-ray flat plate detector comprises an X-ray conversion layer 6, a semiconductor photoelectronic conversion layer 4, a second insulation layer 9, a first electrode 3 and a second electrode (not shown in the figure, and they are arranged in parallel and in a same layer), a first insulation layer 2 and a thin film transistor 1 successively arranged from top to bottom, wherein, the semiconductor photoelectronic conversion layer 4 is configured to convert a light signal into an electronic signal, the second electrode is in contact with the semiconductor photoelectronic conversion layer 4 via a through hole penetrating through the second insulation layer 9 to stabilize the electronic signal converted by the semiconductor photoelectronic conversion layer 4, and the first electrode 3 is connected to a source electrode of the thin film transistor 1 to sense the electronic signal, and transmit the electronic signal to the data processing circuit when the thin film transistor 1 is turned on.
The inventors found that there are at least following problems in the prior art: although the X-ray flat plate detector disclosed in the U.S. patent application has a structure of vertical layout and thus can reduce signal interference, it needs to form a through hole in the second insulation layer 9 to make the second electrode, which is provided to stabilize the electronic signal converted by the semiconductor photoelectronic conversion layer 4, contact the semiconductor photoelectronic conversion layer 4, resulting in a complex process, and since the first electrode 3 and the second electrode are arranged in a same layer, both of them are not continuous plate-like electrodes, thereby the electronic signal sensed by the first electrode 3 is not strong, the electronic signal transmitted to the thin film transistor 1 is also not well, the detection precision is affected.